JP2002263814A - Method for injection-molding low melting point alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for injection-molding a low melting point alloy with which a storing quantity for material in a cylinder is automatically held in the range of the upper and the lower limit values and the good injection- molding can be performed. SOLUTION: This method for injection-molding the low melting point alloy is performed, with which, in the injection-molding process of the low melting point alloy, the upper limit value Qmax of the material storing quantity Q and the control lower limit value CQmin in the cylinder 12 are set so as to eliminate the excess and short of the material storing quantity Q in the cylinder 12. The material storing quantity in the cylinder is automatically held in the range of the upper and the lower limit values by continuing to supply the material having the quantity more than the shot weight Qout into the cylinder till the quantity Q reaches the upper limit value, and by supplying the material having the quantity less than the shot weight till the quantity Q reaches the lower limit value. Then, time loss caused by an unstable weight in a molding machine is reduced and a number of workers for adjusting the condition become unnecessary, and the cost can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low-melting point alloy injection molding method, and more particularly to a method for melting a low-melting point alloy as a molding material in a cylinder of a screw-type low-melting point alloy injection molding machine, and using a screw to form a molding die. The present invention relates to a low-melting-point alloy injection molding method for performing injection molding into a cylinder, supplying an appropriate amount of material from a material supply device in response to a shot, and controlling the material retention amount in a cylinder to be appropriately maintained.

[0002]

2. Description of the Related Art Conventionally, there are a die casting method and a metal injection molding method as an injection molding method of a low melting point alloy. Here, the low melting point refers to a temperature up to about 700 ° C., and specific materials to be used include Al, Mg, Zn, Bi, Sn, and Pb alloys. As shown in FIG. 1 (a), a low melting point alloy injection molding machine using an in-line screw such as a metal injection molding method has a screw type, a belt type, or a vibration type for supplying material chips of a low melting point alloy. A material supply device 16 such as a formula, a screw 11 for transporting and melting the supplied material, a cylinder 12, a heater 13,
It comprises a nozzle 14 for injecting and ejecting the molten material into a mold 19, a high-speed injection device 17, and the like.

In the above-described low melting point alloy injection molding machine, FIG.
As shown in (b), a chip-shaped material obtained by cutting an ingot is used as a raw material. In the low melting point alloy injection molding machine, the material stored in the hopper of the material supply device 16 is supplied into the cylinder 12 by the material supply device 16. The supplied material is transferred forward in the cylinder 12 by rotation of a screw 11 arranged in the cylinder 12 so as to be able to rotate and reciprocate. While being transferred, the material is brought into a predetermined molten state by heating a heater 13 (such as an electric heater or an induction heater) attached to the outer peripheral portion of the cylinder 12.

At the time of the above-mentioned heating, the screw 11 keeps the molten material (light metal melt) in the storage section 15 at the tip of the screw 11 while rotating in the cylinder 12 and at the same time, feeds the material at a constant speed. Retreat to the side. The material in a molten state was collected in the reservoir 15 by retraction amount is weighed. That is, when the screw 11 reaches a predetermined retraction stroke by rotation of the screw 11, the rotation and the retraction movement of the screw 11 are terminated, whereby the measurement of the predetermined amount of the light metal melt corresponding to the retraction stroke is completed. . In the injection step after completion of the measurement, the screw 11 is advanced at a high speed by the high-speed injection device 17 and the light metal melt measured in the storage unit 15 is supplied to the cylinder 1.
The molten metal is poured into the mold 19 through the nozzle 14 at the tip of the second.

[0005]

SUMMARY OF THE INVENTION Such a low melting point alloy
In an injection molding machine, the screw rotation load
The pressure may increase and the screw speed may fluctuate.
When this occurs, the next shot will fire
The amount of molten metal to be used will vary. This rotation
The increase in load pressure is related to the amount of material retained in the cylinder,
Experience that occurs when material retention exceeds the upper limit
I know it. That is, the amount of material stays
The amount of material chips (material
Supply amount = Q _in) And discharged into the mold by the injection process
Of molten metal (shot weight = Q_{ou t}) And their relationship
And the size relationship between the two
Causes the following state.

(A) Q_in> Q_outFor: shot weight
Because the material supply amount is large, ΔQ
(= Q_in−Q _out) Only increases the amount of material retained in the cylinder Q
Add. As a result, the amount of residence increases with the progress of molding.
ΔQ is accumulated, and the material retention amount Q becomes the upper limit Q_maxmore than
May cause abnormal rotation of the screw.
You. (B) Q_in<Q_outIn case of:
Since the amount of supply is small, ΔQ (= Q_out−Q
_in), The material retention amount Q decreases. As a result,
The accumulated amount of decrease ΔQ is accumulated along with the
Quantity Q is lower limit Q_minShort-shot if
Occurs.

As described above, the amount of material retained in the cylinder has a great effect on the stabilization of measurement of the low-melting point alloy injection molding machine. Adjustment of molding conditions is performed to perform molding. As a specific countermeasure, while observing changes in rotational load pressure, or filling conditions of molded products,
In order to supply a material corresponding to the shot weight, a set value such as a material supply amount q per unit time or a supply time t _s of the material supply device is adjusted based on experience. However, due to variations in shot weight, variations in the material supply amount by the material supply device, or changes in the molten state of the material in the cylinder due to temporary machine stoppage, etc., the amount of retained material is stably and continuously reduced. Was difficult to maintain.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. In the injection molding process of a low melting point alloy, the material staying in a cylinder is eliminated in order to eliminate the excess or shortage of the material staying in the cylinder. It is an object of the present invention to provide a low melting point alloy injection molding method in which an upper limit value and a lower limit value of an amount are set, and a material stagnation amount in a cylinder is automatically maintained within the set upper and lower limit values.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a method of melting a low-melting alloy as a molding material in a cylinder of a screw-type low-melting alloy injection molding machine and forming the material by a screw. Injection molding method for low-melting alloys, which is injected into a mold and molded, supplies an appropriate amount of material from a material supply device in response to shots, and controls so as to appropriately maintain the amount of material retained in a cylinder. in the unit increment (Delta] Q ⁺⁾ and the unit decrease amount (Delta] Q ^-), and set the upper limit of the material retention amount (Q _max) and lower control limit of (CQ _min), for each shot weight (Q _out) unit increment amount (Delta] Q ⁺⁾ by more material _{(Q in = Q out + ΔQ} +) to supply running injection step, the quantity of material detained in the cylinder due to the accumulation of the unit increment (ΔQ ⁺⁾ (Q) is an upper limit when it reaches the value (Q _max) , The material supply amount (Q _in) unit decrement amount than the shot weight (Q _out) (ΔQ ^-) only little material ^{_{(Q in = Q out -ΔQ -}} ) Change in the supply of, after the change, the more the injection process run the unit decrease amount (Delta] Q ^-) when the quantity of material detained in the cylinder by the cumulative (Q) has reached the lower limit value (CQ _min), from the shot weight material supply amount (Q _in) (Q _out) Also returns to the supply of the material by the unit increment (ΔQ ⁺ ), and the amount of material retained in the cylinder (Q)
Is automatically repeated to keep the material retention amount (Q) in the cylinder optimal.

According to such a configuration, the amount of retained material (Q) is limited to the upper limit value (Q _max ) and the control lower limit value (CQ _min ).
Is between, for each shot, a unit increment than the shot weight (Delta] Q ⁺⁾ by more material if _{(Q in = Q out + ΔQ} +) supplied with, the cylinder due to the accumulation of the unit increment (Delta] Q ⁺⁾ Reaches the upper limit (Q _max ). Therefore, the material supply amount (Q _in) unit decrement amount than the shot weight (Q _out) the (Delta] Q ^-) only little material ^{_{(Q in = Q out -ΔQ -}} ) is changed to the supply of. Therefore, when the injection process is repeated, the unit decrease amount (ΔQ ⁻ )
Accumulates, the material retention amount (Q) in the cylinder reaches the control lower limit value (CQ _min ). Therefore, the material supply amount (Q
_in ) is increased by a unit (Δ) over the shot weight (Q _out ).
Returning to the supply of material by Q ⁺ ), the material retention amount (Q) in the cylinder is increased. Supply of these materials (Q _in )
By automatically repeating the change, the material accumulation amount (Q) in the cylinder is kept within the range of the upper limit value (Q _max ) and the control lower limit value (CQ _min ). Can be prevented. In the present invention, in order to calculate that the material retention amount (Q) has reached the upper limit value (Q _max ) and the control lower limit value (CQ _min ), the shot weight (Q _out ) is measured by a weight measurement sensor. Try to measure automatically or manually.

In the present invention, at least one of the rotational load pressure, the back pressure, and the screw rotation time during screw rotation is used to detect that the upper limit value (Q _max ) has been reached. As a result, the present invention can be carried out using the conventionally arranged detecting means.

Further, in the present invention, when changing the material supply amount, the unit increment (Delta] Q ⁺⁾ and the unit decrease amount (Delta] Q ^-) stepwise changed. This is to prevent the molten state of the material in the cylinder from suddenly changing and causing a quality abnormality.

Further, in the present invention, in the case of the stepwise change, the unit increment applied within the specified time (Delta] Q ⁺⁾ and the unit decrement ^- provisions alters the per se, are applied (Delta] Q) Change the time. This facilitates the programming of the control program.

Further, in the present invention, an alloy chip of Mg, Al, Zn, Sn, Pb and Bi is used as the molding material. According to these materials, it is easy to obtain,
It is also suitable for implementing the present invention in terms of properties.

Summarizing the important points of the above description, and more specifically, the low melting point alloy injection molding method for stabilizing the metering without causing an increase in the rotational load pressure directly reduces the material stagnation in the cylinder. That is, control is performed within the range of the upper and lower limits of the staying amount by predicting indirectly or indirectly.
That is, when the material Q _in (= Q _out + ΔQ ⁺ ) that is larger by ΔQ ⁺ than the shot weight Q _out is supplied, and the accumulated amount of material in the cylinder reaches the upper limit value Q _{max due} to the accumulation of ΔQ ⁺ , than the shot weight Q _out of material supply amount Q _in Delta] Q ^- only small amount (= Q _out -ΔQ ^-) is changed to reduce the quantity of material detained in the cylinder. On the other hand, when the material the amount of retention when there is a decreasing tendency, the material retention amount has reached the large set control limit value CQ _min than the lower limit value Q _min of the material retention amount was experimentally determined in advance, the material Supply Q _in
Is again changed to a value larger by ΔQ ⁺ than the shot weight Q _out to increase the amount of retained material. As described above, stable weighing is realized by performing molding while repeatedly decreasing or increasing the amount of material retained in the cylinder within the range of the upper and lower limits.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 2 is a view showing a material retention amount, a material supply amount, a shot weight, a back pressure during rotation of a screw and a rotation when a low melting point alloy injection molding method of the present invention is applied to the low melting point alloy injection molding machine of FIG. 3 is a time chart showing a change in load pressure, FIG. 3 is a graph illustrating a relationship between a material supply time and a material supply amount of a material supply device, FIG. 4 is a flowchart illustrating an example of a control operation according to the present invention, and FIG. 5 is a flowchart illustrating another example of the control operation according to the present invention.

In the time chart of FIG. 2, the display of the horizontal axis indicates the total shot number (SH1, SH) instead of time.
2,-). When the operation of the molding machine is started from a state where there is no material inside the cylinder 12, in order to prevent the occurrence of a short shot, the lower limit value Q of the material retention amount Q is set.
introducing the material for any amount Qi in the range of the upper limit value Q _max from _min (initial material input).

The lower limit value Q _min and the upper limit value Q _max of the material retention amount Q need to be experimentally determined in advance. Method of determining the upper limit value Q _max of the material retention amount Q is shot weight Q _out
Than ΔQ ⁺ only large amount of material _{(Q in = Q out + ΔQ} +)
Is performed while supplying the shot weight Q at that time.
_out , the rotation load pressure, the back pressure, and the screw rotation time are measured, and the material retention amount Q is calculated by the following equation.

[0019] _{Q = Q'+ Q in -Q out} Q': quantity of material detained before shot

Then, the material retention amount Q at the time when it is confirmed that the rotational load pressure and the back pressure increase or the screw rotational time is shortened is set to an upper limit value _Qmax . Furthermore, the upper limit value Q _max
There after being observed, and change the quantity of material fed to the ΔQ' by an amount smaller than the shot weight _{Q out (Q in = Q out} -ΔQ'), to continue the molding. Then, the material retention amount Q at the time the short shot occurs as the lower limit Q _min, to a value close to the middle of the Q _max and Q _min and the control lower limit value CQ _min. During this molding operation, the average value of the measured shot weights (excluding short shots) AQ _out is calculated.

When the initial material is charged, the screw 1
1 is a state in which only the rotation operation is performed at the most advanced position, and while the material is supplied from the material supply device 16, the material is supplied continuously or intermittently in 2 to 5 times until the material retention amount Q reaches the predetermined amount Qi. I do.

In the weighing operation to be performed after the initial material input, the screw is rotated at a constant speed until the predetermined stroke commensurate with the shot weight _Qout while rotating the screw 11, and is retracted. During the weighing operation, from the material supply device 16, the expected shot weight Q unit increment ΔQ than _out ⁺ only greater amount of material (Q _in = Q _out +
ΔQ ⁺ ) is supplied in a manner interlocked with the start and end of screw rotation, or evenly during a material supply time t _s set shorter than the screw rotation time. Thus, if than the shot weight Q _out of material supply amount Q _in molded with many supplied by Delta] Q ^+, the material retention amount Q in the cylinder 12 is increased linearly, for example, the number of shots SH
By the time it reaches 1, the upper limit value _Qmax is reached.

In the above case, there are the following two methods for determining whether or not the upper limit value _Qmax has been reached. That, (a) the shot weight Q _out is measured for each shot, accumulates the difference between the shot weight Q _out and the material supply amount ^{_{Q in (ΔQ + = Q in}} -Q out), direct material retention amount Q To figure out. Alternatively, (b) when the material retention amount Q reaches the upper limit value _Qmax , as shown in FIG. 2, the back pressure during rotation of the screw or the rotational load pressure increases, or the screw rotation time becomes shorter. By grasping the change, the material retention amount Q is indirectly grasped.

[0024] The material accumulation by the methods (a) and (b) as described above.
Remaining quantity Q is upper limit Q_maxWhen it is detected that
Is the material supply amount Q_inThe shot weight Q_outΔQ than^-Is
Change the supply so that it is supplied in a smaller amount. Thus, the material
Feed supply Q_inThe shot weight Q_outΔQ than^-Only few
When the molding is performed while supplying under the conditions, the cylinder 12
The material retention amount Q inside decreases linearly (example
For example, the shot numbers SH1 to SH2). In this case, the material
Remaining amount Q is lower limit value Q_minNot less than
Therefore, the material retention amount Q is determined by the following two methods.
Predict. That is, (c) shot weight Q_outThe
Measured for each shot, and shot weight Q_outAnd material supply Q
_in(ΔQ^-= Q_out−Q_in) Is accumulated and the amount of material stays
Grasp Q directly. Or (d) material supply amount Q_in
Number m of shots after changing (m = SH2-SH1)
And the decrease ΔQ in the amount of stay for each shot^-And using the material
Detention amount Q = Q_max−m · ΔQ ^-Predict.

The prediction is performed by the methods (c) and (d) as described above.
Material retention amount Q is controlled lower limit value CQ _minReached
Then, the material supply amount Q again_inThe shot weight Q_outΔ than
Q⁺Change to a larger amount. In addition, the material supply amount Q_inIncrease
When adding, the molten state of the material in the cylinder
You can increase it in steps to keep it the same
(The same applies to the case of decreasing). Where the material supply
Quantity Q_inReduces the variation in the amount of material supplied from the material supply device.
Decide in consideration. That is, the material supply amount is
± 1% to ± 5% depending on degree distribution or size
There is inherent variation.

Considering the above facts, the material supply amount
Is ± c% when the material is supplied as shown in FIG.
Interval t_sAnd material supply Q_inFrom the relationship between
Interval t_sBy adjusting according to the following formula, the material
Supply Q_inTo change. That is, the amount of material retention increases
If you want to: t_smax≤t_s≤t_R  Where t_smax= (1 + c / 100) · Q_out/ S To reduce the amount of retained material: t_S≤t_smin Where t_smin= (1-c / 100) · Q_out/ S where t_RIs the screw rotation time, S is the material supply time t_s
Is the material supply amount per unit time that satisfies the above relationship.
You.

In the case of performing the above adjustment, actually, the material retention amount is directly or indirectly controlled by the combination of the above (a) and (c) or the combination of (b) and (d). By predicting the results and feeding back the results to the control system of the molding machine, the material supply amount is automatically adjusted. As described above, if the amount of retained material is controlled within the range of the upper and lower limits while repeatedly increasing and decreasing the amount of supplied material, stable metering without increasing the screw rotation load pressure can be realized.

As an example described above, a control operation by a combination of the method (a) and the method (c) will be described with reference to FIG. First, after the injection, as well as measure the shot weight Q _out of the shot, to calculate the quantity of material fed Q _in from the material supply amount per material supply time and the unit time (step S11). The difference (ΔQ ⁺ = Q _in -Q _out ) between the shot weight Q _out and the material supply amount Q _in is calculated, and this difference is added to the material retention amount (Q ′) at the time of the previous shot (Q = Q). '+ (Q _in -Q _out )) to determine the material retention amount Q (step S12). Here, the shot weight _Qout can be measured automatically by attaching a weight measurement sensor to the molded product take-out machine.

Then, the obtained material retention amount Q is expressed by the following formulas (a), (b), and (c): (a) control lower limit value CQ _min <material retention amount Q <upper limit value Q _max (b) material Remaining amount Q ≦ control lower limit value CQ _min (c) It is determined which one of material retained amount Q ≧ upper limit value Q _max is satisfied (step S1)
3).

As a result of the determination in step S13, if it is determined that the formula (A) is satisfied, the current material supply operation (the material retention amount Q is increased by a unit increment (Δ
Q ⁺⁾ or unit decrease amount (Delta] Q ^-) maintaining operation) of the current to be only changed, the process proceeds to step S17 (step S14). As a result of the determination in step S13, if it is determined that the formula (b) is satisfied, the material supply amount is changed even if the material supply amount has been changed by the unit decrease amount (ΔQ ⁻ ) until then. Q _in which is changed by the unit increment (ΔQ ⁺ )
= Q _out + ΔQ ^{+ and} the process proceeds to step S17 (step S15). If it is determined in step S13 that the formula (c) is satisfied, the material supply amount that has been changed by the unit increase amount (ΔQ ⁺ ) is reduced by the unit decrease amount (ΔQ ⁻ ). Is changed only by Q _in = Q
The operation is switched to the operation of _out- ΔQ- ^and the process proceeds to step S17 (step S16). In step 17, it is determined whether or not the injection molding operation is completed.
1, the operation is continued based on the operations determined in steps S14, S15, and S16.

As another example, a control operation based on a combination of the method (b) and the method (d) will be described with reference to FIGS. In this method, the fact that the material retention amount Q has reached the upper limit value _Qmax is sensed by increasing the rotational load pressure and the back pressure or shortening the screw rotation time, so that setting of the upper limit value is not required. Also,
Shot weight Q _out also becomes possible to use the average shot weight AQ _out weight or a pre-determined empirically calculated from the mold shape, it is not necessary to perform shot weight measurement per shot. In FIG. 8, reference numeral 31 indicates a rotational load pressure measurement point, 32 indicates a back pressure measurement point, and 33 indicates a screw rotation time measurement point. When the injection operation becomes possible and the normal injection operation is started, the back pressure, the rotation load pressure, and the rotation time during the rotation of the screw are measured (step S2).
1). For each of the back pressure, the rotation load pressure, and the rotation time, each determination set value set as a threshold for determining whether or not they are abnormal is compared with the measurement result in step S21. It is determined whether the conditions (d), (e), and (f) have occurred (step S22). That is, (d) back pressure measured value ≧ back pressure determination set value (e) rotation load pressure ≧ rotation load pressure determination set value (f) rotation time ≦ rotation time determination set value

As a result of the determination in step S22, the condition
At least one of (d), (e), and (f) has occurred
In this case, reduce the material supply time and
Q_in= AQ _out−ΔQ^-Let the action run at the same time
The shot count m is set to m = 0 (step S2).
9). As a result of the determination in step S22,
If it is determined that neither (d), (e) nor (f) has occurred
In this case, it is necessary to determine whether the amount of accumulated material is
Perform (Step S23). In step S23,
The process of increasing the amount of stagnation, ie Q_in> QA_outIf it is
Moves to step S28, and the current Q_inIn a situation where
Move to step S30. On the other hand, in step S23
The process of reducing the amount of accumulated material, ie Q_in≤AQ_outIs
In this case, the shot count m is calculated as m = m ′ + 1 (m ′ is
Go to step S25 as (count number of previous shot)
Q = Q_max−mΔQ^-Do more.
The obtained material retention amount Q is calculated by the following formulas (a) and (b), that is, (a) control lower limit value CQ_min<Material retention amount Q (b) Material retention amount Q ≦ Control lower limit value CQ_min Is determined (step S25).

As a result of the determination in step S25, if it is determined that the expression (a) is satisfied, the current material supply operation (the material retention amount Q is reduced by the unit reduction amount (Δ
Q ^-) maintaining operation) of the current to be only changed, the process proceeds to step S30 (step S26). Step S25
Results of the determination, if it is determined to satisfy equation (b), the unit reduction amount with respect to the shot volume Q _out far (Delta] Q ^-) even if it was varied so that only less The operation is switched to the operation of Q _in = Q _out + ΔQ ⁺ for changing the material supply amount so as to increase by the unit increase amount (ΔQ ⁺ ), and the process proceeds to step S30 (step S27). In step S30, it is determined whether or not the injection molding operation is completed. If not, the process returns to step S21, and the process returns to step S26.
The operation is continued based on the operations determined in S27, S28, and S29, respectively.

Next, with reference to FIGS. 6 and 7, a description will be given of a comparative example of a case where the conventional method is used and a case where the method of the present invention is used in molding using the same mold. Using a low melting point alloy injection molding machine with a mold clamping force of 650 Ton, the shot weight of the Mg alloy (AZ91D) was about 3
When a notebook computer case having a capacity of 00 g was molded while adjusting the material supply amount so that the material retention amount was constant as in the past, the screw rotation load pressure tended to increase after molding for about several hours. (FIG. 6). Therefore, the measuring method of the present invention, that is, ΔQ ⁺ = 25 so that the amount of retained material is within the range of the upper and lower limits, is used.
g, Delta] Q ^- = it was molded using the same mold while controlling the quantity of material fed as 20g, even if the continuous molding of about 12 hours, the screw rotational load pressure to maintain a constant low value It was possible to form about 800 shots with a standard deviation of 0.91 (FIG. 7).

In this case, the upper limit value of the material retention amount determined in advance by experiments is about 6000 g, and the lower limit value is about 250 g.
It was 0 g. The control of the amount of retained material was performed while adjusting the material supply by the methods (b) and (d) described above. The threshold value at that time (the reaching of the upper limit was detected by employing the back pressure, and the control lower limit was predicted from the number of shots and the material supply amount) was as follows. << Conditions for reaching the upper limit value >> Back pressure = 0.1 MPa → 0.3 MPa << Conditions for reaching the control lower limit value >> Shot number n = 100 Decrease in material retention ΔQ ⁻ = 20 g Control lower limit value CQ _min = Q _max −n · ΔQ ^- = 6000-1
00 × 20 = 4000 (g)

[0036]

The method of injection molding a low melting point alloy according to the present invention comprises:
The configuration as described above has the following effects. The problem of metering instability in low-melting point alloy injection molding machines can be solved by directly and indirectly predicting and controlling the amount of material remaining in the cylinder, which is one of the causes, to increase the screw rotational load pressure abnormally It is possible to solve the problem of weighing instability such as inability to rotate.
Furthermore, the molding machine can be grasped by measuring the amount of material retained by measuring the shot weight of each shot or by estimating the amount based on changes in back pressure, rotation load pressure, and rotation time during screw rotation. Can be fed back to the control system, and the condition adjustment that has been empirically performed by the operator can be automated. As a result, downtime due to unstable measurement of the molding machine can be reduced, and personnel for adjusting conditions are not required, so that cost can be reduced.

[Brief description of the drawings]

FIG. 1 (a) is a configuration diagram showing a low melting point alloy injection molding machine. (B) is a figure explaining the chip-shaped material used in (a).

FIG. 2 is a diagram illustrating a low-melting point alloy injection molding method according to the present invention applied to the low-melting point alloy injection molding machine of FIG. 1; It is a time chart which shows the change of load pressure.

FIG. 3 is a graph illustrating a relationship between a material supply time and a material supply amount of a material supply device.

FIG. 4 is a flowchart illustrating an example of a control operation according to the present invention.

FIG. 5 is a flowchart illustrating another example of the control operation according to the present invention.

FIG. 6 is a time chart showing changes in rotational load pressure, shot weight, material supply amount, and material stagnation amount when a conventional method is used in a comparative example.

FIG. 7 is a time chart showing changes in rotational load pressure, back pressure, shot weight, material supply amount, and material retention amount in a comparative example according to the present invention.

FIG. 8 is a diagram showing detection positions of back pressure, rotation load pressure, and rotation time.

[Explanation of symbols]

11 screw 12 cylinder 13 heater 14 nozzle 15 reservoir 16 material feeder 17 speed injection device 19 mold Q material retention amount Q _max limit Q _min limit value CQ _min control lower limit Q _in material supply quantity Q _out shot weight Delta] Q ⁺ unit increment Delta] Q ^- unit decrement amount SH1, SH2, ~ total number of shots S11~S28 step

Claims (6)

[Claims] A low melting point alloy as a molding material is screwed.
Molten in the cylinder of a low melting point alloy injection molding machine
While injecting and molding into the molding die with a screw,
Proper amount of material from material supply device corresponding to shot
Supply and maintain the material retention amount in the cylinder properly.
In the low-melting alloy injection molding method, the unit increase (ΔQ⁺) And unit reduction (ΔQ^-),material
The upper limit of the amount of residence (Q_{ma x}) And control lower limit (CQ_min)
And set each shot weight (Q_out) To the unit increase (ΔQ⁺)
Material (Q_in= Q_out+ ΔQ⁺) Supply the injection mechanic
And the unit increment (ΔQ⁺A) by accumulation of
Material retention amount (Q) in the_max) Reached
When the material supply amount (Q_inA) shot weight
(Q_out) Than the unit decrease (ΔQ^-Only) less material
(Q_in= Q_out−ΔQ^-) Supply, and after the change, further execute the injection process to reduce the unit
Q^-) Accumulates the material retention amount (Q) in the cylinder
Control lower limit (CQ_min), The material supply
(Q_in) To the shot weight (Q_out) Unit increase than
(ΔQ⁺) Return to supply of more material
Automatically increase the charge retention amount (Q),
The feature is to keep the amount of retained material (Q) in the cylinder optimal.
Low melting alloy injection molding method. 2. The shot weight (Q _out ) is automatically or automatically measured by a weight measuring sensor in order to calculate that the material retention amount (Q) has reached the upper limit value (Q _max ) and the control lower limit value (CQ _min ). The method according to claim 1, wherein the measurement is performed manually. 3. In order to detect that the upper limit value (Q _max ) has been reached, a rotational load pressure during screw rotation, a back pressure,
2. The method according to claim 1, wherein at least one of the screw rotation times is used. 4. The low melting point according to claim 1, wherein when the material supply amount is changed, the unit increase amount (ΔQ ⁺ ) and the unit decrease amount (ΔQ ⁻ ) are changed stepwise. Alloy injection molding method. 5. The method according to claim 1, wherein the stepwise change includes changing a unit increase amount (ΔQ ⁺ ) and a unit decrease amount (ΔQ ⁻ ) applied within a specified time, or changing the applied specified time. Item 5. A low melting point alloy injection molding method according to Item 4. 6. The molding material is Mg, Al, Z.
A low-melting-point alloy injection molding method characterized by using an alloy chip of n, Sn, Pb, and Bi.